This invention relates generally to chain construction, and more particularly to sprocket chains made up of a series of identical links hingedly connected together by pivot pins. More specifically, the present invention deals with an improved sprocket chain composed of interconnecting links and pivot pins of synthetic resin composition and adapted especially for use in normally corrosive environs such a sewage treatment plants, sludge settling tanks and the like.
While the prior art, as typified by U.S. Pat. Nos. 3,127,980 and 3,138,236, teaches chain links formed of corrosion-resistant plastics or synthetic resins and which may be resiliently flexed to facilitate connection and disconnection of one link from another, so far as I am aware, the prior art does not disclose or make obvious a sprocket chain made up of a number of identical links of synthetic resin composition pivotally or hingedly joined by quickly detachable, twist-locking pivot pins also formed from a corrosion-resistant synthetic resin, and wherein the pivot pins are constructed and arranged to cooperate with a cam-type locking surface on each link to provide a resiliently-pressed snap-locking engagement between the pivot pin and chain link.
Also, the prior art discloses numerous different forms and constructions of sprocket chains made up of a plurality of identical metal links pivotally connected by transverse pivot pins. See, for example, U.S. Pat. Nos. 1,608,340; 2,124,912; 2,259,880; 2,420,256 and 2,810,297. However, so far as I am aware, the prior art is devoid of any sprocket chain composed of a plurality of identical, clevis-like links which are pivotally or hingedly connected by twist-locking pivot pins, and wherein the pivot pins are formed with cam-follower lugs or detents engageable with cam-type locking surfaces on the links to initially flex the opposite eyes of the links toward one another and then cause the eyes of the links to snap outwardly to releasably lock the pin lugs to the links.